chore: ensure metrics are correctly exposed (#761)

* chore: ensure metrics are correctly exposed

* add changelog entry

* small refactoring for service name functions

Author: xeniape

CHANGELOG.md

@@ -8,6 +8,7 @@ All notable changes to this project will be documented in this file.
 
 - Helm: Allow Pod `priorityClassName` to be configured ([#752]).
 - Add support for `34.0.0` ([#755]).
+- Add `prometheus.io/path|port|scheme` annotations to metrics services ([#761]).
 
 ### Changed
 
@@ -31,6 +32,7 @@ All notable changes to this project will be documented in this file.
 [#753]: https://github.com/stackabletech/druid-operator/pull/753
 [#755]: https://github.com/stackabletech/druid-operator/pull/755
 [#756]: https://github.com/stackabletech/druid-operator/pull/756
+[#761]: https://github.com/stackabletech/druid-operator/pull/761
 
 ## [25.7.0] - 2025-07-23
 

rust/operator-binary/src/druid_controller.rs

@@ -73,10 +73,11 @@ use crate::{
         Container, DB_PASSWORD_ENV, DB_USERNAME_ENV, DRUID_CONFIG_DIRECTORY, DS_BUCKET,
         DeepStorageSpec, DruidClusterStatus, DruidRole, EXTENSIONS_LOADLIST, HDFS_CONFIG_DIRECTORY,
         JVM_CONFIG, JVM_SECURITY_PROPERTIES_FILE, LOG_CONFIG_DIRECTORY, MAX_DRUID_LOG_FILES_SIZE,
-        OPERATOR_NAME, RUNTIME_PROPS, RW_CONFIG_DIRECTORY, S3_ACCESS_KEY, S3_ENDPOINT_URL,
-        S3_PATH_STYLE_ACCESS, S3_SECRET_KEY, STACKABLE_LOG_DIR, ZOOKEEPER_CONNECTION_STRING,
-        authentication::AuthenticationClassesResolved, authorization::DruidAuthorization,
-        build_recommended_labels, build_string_list, security::DruidTlsSecurity, v1alpha1,
+        METRICS_PORT, METRICS_PORT_NAME, OPERATOR_NAME, RUNTIME_PROPS, RW_CONFIG_DIRECTORY,
+        S3_ACCESS_KEY, S3_ENDPOINT_URL, S3_PATH_STYLE_ACCESS, S3_SECRET_KEY, STACKABLE_LOG_DIR,
+        ZOOKEEPER_CONNECTION_STRING, authentication::AuthenticationClassesResolved,
+        authorization::DruidAuthorization, build_recommended_labels, build_string_list,
+        security::DruidTlsSecurity, v1alpha1,
     },
     discovery::{self, build_discovery_configmaps},
     extensions::get_extension_list,
@@ -87,10 +88,7 @@ use crate::{
     },
     operations::{graceful_shutdown::add_graceful_shutdown_config, pdb::add_pdbs},
     product_logging::extend_role_group_config_map,
-    service::{
-        build_rolegroup_headless_service, build_rolegroup_metrics_service,
-        rolegroup_headless_service_name,
-    },
+    service::{build_rolegroup_headless_service, build_rolegroup_metrics_service},
 };
 
 pub const DRUID_CONTROLLER_NAME: &str = "druidcluster";
@@ -1078,6 +1076,7 @@ fn build_rolegroup_statefulset(
         .args(vec![main_container_commands.join("\n")])
         .add_env_vars(rest_env)
         .add_container_ports(druid_tls_security.container_ports(role))
+        .add_container_port(METRICS_PORT_NAME, METRICS_PORT.into())
         // 10s * 30 = 300s to come up
         .startup_probe(druid_tls_security.get_tcp_socket_probe(30, 10, 30, 3))
         // 10s * 1 = 10s to get removed from service
@@ -1220,9 +1219,7 @@ fn build_rolegroup_statefulset(
                 ),
                 ..LabelSelector::default()
             },
-            service_name: Some(rolegroup_headless_service_name(
-                &rolegroup_ref.object_name(),
-            )),
+            service_name: Some(rolegroup_ref.rolegroup_headless_service_name()),
             template: pod_template,
             volume_claim_templates: pvcs,
             ..StatefulSetSpec::default()

rust/operator-binary/src/service.rs

@@ -4,17 +4,14 @@ use snafu::{ResultExt, Snafu};
 use stackable_operator::{
     builder::meta::ObjectMetaBuilder,
     k8s_openapi::api::core::v1::{Service, ServicePort, ServiceSpec},
-    kvp::{Label, ObjectLabels},
+    kvp::{Annotations, Label, ObjectLabels},
     role_utils::RoleGroupRef,
 };
 
 use crate::crd::{
     DruidRole, METRICS_PORT, METRICS_PORT_NAME, security::DruidTlsSecurity, v1alpha1,
 };
 
-const METRICS_SERVICE_SUFFIX: &str = "metrics";
-const HEADLESS_SERVICE_SUFFIX: &str = "headless";
-
 #[derive(Snafu, Debug)]
 pub enum Error {
     #[snafu(display("object is missing metadata to build owner reference"))]
@@ -46,9 +43,7 @@ pub fn build_rolegroup_headless_service(
     Ok(Service {
         metadata: ObjectMetaBuilder::new()
             .name_and_namespace(druid)
-            .name(rolegroup_headless_service_name(
-                &role_group_ref.object_name(),
-            ))
+            .name(role_group_ref.rolegroup_headless_service_name())
             .ownerreference_from_resource(druid, None, Some(true))
             .context(ObjectMissingMetadataForOwnerRefSnafu)?
             .with_recommended_labels(object_labels)
@@ -77,14 +72,13 @@ pub fn build_rolegroup_metrics_service(
     Ok(Service {
         metadata: ObjectMetaBuilder::new()
             .name_and_namespace(druid)
-            .name(rolegroup_metrics_service_name(
-                &role_group_ref.object_name(),
-            ))
+            .name(role_group_ref.rolegroup_metrics_service_name())
             .ownerreference_from_resource(druid, None, Some(true))
             .context(ObjectMissingMetadataForOwnerRefSnafu)?
             .with_recommended_labels(object_labels)
             .context(MetadataBuildSnafu)?
             .with_label(Label::try_from(("prometheus.io/scrape", "true")).context(LabelBuildSnafu)?)
+            .with_annotations(prometheus_annotations())
             .build(),
         spec: Some(ServiceSpec {
             // Internal communication does not need to be exposed
@@ -108,12 +102,17 @@ fn metrics_service_ports() -> Vec<ServicePort> {
     }]
 }
 
-/// Returns the metrics rolegroup service name `<cluster>-<role>-<rolegroup>-<METRICS_SERVICE_SUFFIX>`.
-fn rolegroup_metrics_service_name(role_group_ref_object_name: &str) -> String {
-    format!("{role_group_ref_object_name}-{METRICS_SERVICE_SUFFIX}")
-}
-
-/// Returns the headless rolegroup service name `<cluster>-<role>-<rolegroup>-<HEADLESS_SERVICE_SUFFIX>`.
-pub fn rolegroup_headless_service_name(role_group_ref_object_name: &str) -> String {
-    format!("{role_group_ref_object_name}-{HEADLESS_SERVICE_SUFFIX}")
+/// Common annotations for Prometheus
+///
+/// These annotations can be used in a ServiceMonitor.
+///
+/// see also <https://github.com/prometheus-community/helm-charts/blob/prometheus-27.32.0/charts/prometheus/values.yaml#L983-L1036>
+fn prometheus_annotations() -> Annotations {
+    Annotations::try_from([
+        ("prometheus.io/path".to_owned(), "/metrics".to_owned()),
+        ("prometheus.io/port".to_owned(), METRICS_PORT.to_string()),
+        ("prometheus.io/scheme".to_owned(), "http".to_owned()),
+        ("prometheus.io/scrape".to_owned(), "true".to_owned()),
+    ])
+    .expect("should be valid annotations")
 }